diff --git a/lib/mmmail.rb b/lib/mmmail.rb
index c198e63..72012fd 100644
--- a/lib/mmmail.rb
+++ b/lib/mmmail.rb
@@ -73,7 +73,7 @@ def []=(k, v) @headers[translate_header_to_sym(k)] = v end
     
     def method_missing(sym, *args)
       if sym.to_s =~ /=$/
-        self[sym.to_s[0..-2].to_sym] = *args
+        self[sym.to_s[0..-2].to_sym] = args.first
       elsif @headers.has_key?(sym)
         self[sym]
       else